1. Field of the Invention
The present invention relates to a vehicle surroundings monitoring apparatus in which object extraction is carried out by subjecting an image to a binarization processing.
Priority is claimed on Japanese Patent Application No. 2004-175668, filed Jun. 14, 2004, the content of which is incorporated herein by reference.
2. Description of Related Art
Vehicle surroundings monitoring apparatuses have been employed in which objects that may collide with the vehicle, such as pedestrians, are extracted from a picture around the vehicle captured by an infrared camera. More specifically, in the device, the captured infrared image is subjected to a binarization processing, and an area (binarized object) in which bright portions are concentrated is searched for. Then, it is determined whether or not the area is a head portion of a pedestrian by using the aspect ratio (ratio of length to width) and the sufficiency rate of the binarized object, and further calculating the distance between the vehicle and the binarized object using the actual surface area and the position of the centroid in the image. If the area of the head portion of a pedestrian is determined, an area which contains the body of the pedestrian is determined and set. These areas are displayed to be distinguished from the other regions of the image. In this manner, the position of the entire body of the pedestrian in the infrared image is determined, and this information is displayed for the driver so as to effectively assist the vision of the driver (refer to Japanese Unexamined Patent Application, First Publication No. H11-328364, for example).
However, when a vehicle is traveling, due to the influence in change in the geometry of a road ahead, or the pitching of the vehicle, the shape of the binarized object does not necessarily reflect the actual shape of the object.
Consequently, in order to provide an effective visual assistance to the driver, in addition to extracting pedestrians based on physical characteristics that can be distinguished relatively easily, such as a shape identification based on the presence of an object that has an equivalent height as a human height in the object image, a shape identification based on the presence of the head and the torso, and a shape identification based only on the head, or the like, that are used in device described in Japanese Unexamined Patent Application, First Publication No. H11-328364, it is necessary to extract artificial structures, such as road constructions, from a binarized object and then distinguish between objects other than pedestrians and pedestrians.